Albert l



UNITED STATES PATENT OFFICE.

ALBERT L. CLAPP, 0F MARBLEHEAD,MASSACHUSETTS. ASSIGNOR T0 REGINALD W. BIRD, 0F FRAMINGHAM, MASSACHUSETTS.

FELT AND METHOD OF MAKING THE SAME.

No Drawing.

To all whom it may concern:

Be it known that I, ALBERT L. CLArr, a citizen of the United States, residing at Marblehead, in the county of Essex and State of Massachusetts, have invented new and useful Improvements in Felts and Methods of Making the Same, of which the following is a specification.

This invention has relation to the art of felt-making and also relates to the manufacture of prepared weatherproof roofing material.

1n the manufacture of artificial or prepared shingles or sheet roofing there are used certain weatherproof pitchy asphaltic bituminous or hydrocarbon compounds of such character that they will withstand solar heat and the action of the elements, when exposed on the roof or side of a building. Various materials of this general character are used for impregnating and for coating the roofing material. It is preferable for the saturating compound, however, to employ those materials which have a relatively low melting point, and to use for the coating or facing materials having a relatively higher melting point and which are relatively tough and hard. These various materials cannot be used alone, i. 6., formed in thin slabs, and consequently it is necessary to use some sort of porous foundation or support therefor. Heretofore it has been customary to utilize for this purpose what is known as felt, which consists largely of rag fibers, sometimes with a small amount of wool fiber incorporated therein. Such felt of the desired thickness is first impregnated with the saturating compound, which may consist of a low-melting-point asphalt or a mixture of soft asphalts, rosins, oils, wax tailings, etc. The saturating compound is rendered molten by heat and the sheet of felt is carried therethrough. Then there is applied to one or both faces of the impregnated sheet a coating of a relatively harder compound, such as higher-melting-point asphalt or a mixture of pitches and asphalts. Sometimes there is incorporated in the coating pigments of an inert nature which impart their color thereto. For this purpose red iron oxid is frequently used.

According to modern practice, however,

Specification of Letters Patent.

Patented une 3, 1919.

Application filed August 21, 1916. Serial No. 116,163.

it is customary while the exterior coating is soft and plastic, to apply thereto a thick facing or layer of crushed slate, grit, or other granular comminuted or crushed material, the ranules of which are partially embedded in the soft and plastic coating. Ornamental effects are secured by using mineral materials of different colors and applying them in designs in spaced areas on the surface of the sheet.

The support or foundation, which serves as the medium for holding in place the saturating waterproofing compound and the exterior coatings or facings, must be of such character that the molten saturating compound may easily penetrate it within a short space of time. In order that the roofing material may be produced at low cost, it is necessary that the sheet of felt or the sheet forming the support should be fed through the molten bath of saturating compound at a relatively high speed, and it will be understood by those skilled in the art that the greater the degree to which the support is saturated, the greater will be the durability thereof. According to the requirements of the National Board of Under- Writers, prepared roofing used for shingles or the like must have at least a certain minimum weight per square foot. Hence, if the foundation or support is characterized by slow penetrability, the saturating compound must be so soft that it is impracticable and will, when the roofing is laid, ooze from the roofing, or else the compound must be heated to such a degree of temperature as to injure the foundation or support as it is passing therethrough.

After long experimentation, I have succeeded in producing, for use as a foundation or support for roofing material, what may be termed a felt which is characterized by three optimum characteristics: First, it is of suflicient strength to withstand the strains to which it is exposed during the impregnation and coating operations; second, it has a high degree of penetrability so that it may be saturated to a maximum extent more rapidly than heretofore found practicable; and, third, it is of Such flexibility that, after being saturated and coated, it does not readily break when bent at a relatively sharp of leather to 25 parts by Weight ofsawdust.

angle. I have succeeded in producing a composition of matter which may be supplied to felt makers for admixture with the usual rag fiber that is employed 1n the manufacture of felt and which, therefore, will form an article of commerce and be sold in bulk.

My composition of matter contalns'as its basic element finely shredded leather, preferably sole leather, although upper leather may, durin the scarcity of sole leather, employed or the purpose. The leather s shredded or ground to a soft fibrous condition. The second element of the composition of matter is preferably fine sawdust or its equivalent. The sawdust is preferably so fine that it will not form lumps in the subsequently manufactured felt. If ordinary sawdust is used, it should be screened and only that portion utilized. which will pass through a 25 to 50 mesh sieve in order to secure the best results. These two'materials' should preferably, although not necessarily, be thoroughly mixed together and then be shipped in bulk. I may, for instance, employ a mixture containing 35 parts by welght In lieu of the sawdust, I may substitute either finely ground charcoal or shredded peat. I find, however, that better results are obtained by using with the leather fiber as a composition of matter, charcoal in addition to the sawdust, and that, indeed, I may employ all four materials, to wit, leather, charcoal, sawdust and peat. Peat is fibrous whereas charcoal and sawdust are more or less granular. The latter serve an important function in that, when finally incorporated in the felt, they space or separate the fibers and leave relatively large voids or interstices for the reception of the saturating compound.

I may, for example, form the composition of matter of leather, 20 parts by weight; charcoal, 20 parts by weight; and sawdust, 20 parts by weight; or I may employ leather, 20 parts by weight; charcoal, 10 parts by weight; sawdust, 10 parts by weight; and shredded peat, 10 parts by weight. These materials, according to the formula used, are preferably thoroughly mixed together and then may be baled for shipment.

In the manufacture of the felt, I preferably employ approximately 40 to 55 parts by weight of rag fibers to parts by weight of my composition of matter; although these proportions may be changed as desired. The

' rags, with the proper amount of water, are

first placed in the heater and subjected to disintegration for about an hour. Then the composition of matter is added and the whole mass beaten for about an hour and a half, until the stock is homogeneous and of the proper consistency. Then it is formed into sheets according to the usual manner. I

sired tensile strength because of the presence of the leather fibers. And because of the presence of the fine particles of finely ground charcoal or of the sawdust, or both, the felt is full of voids and interstices into which thesaturated compound may penetrate with great rapidity even though it be of a relatively high melting point. I find that such felt is capable of absorbing and obtaining a greater weight of saturating compound per square foot than ordinary felt of the same thickness manufactured of rag fiber, or a mixture of rag fiber and paper stock such as is now commonly used, and that a sheet may be passed through the saturating bath at higher speed than heretofore, and yet absorb a relatively greater quantity of the saturating compound, than other previous materials.

Care must be taken that the spacing materials, to wit, the charcoal or the sawdust, or both, should be in a state of fine subdivision. If fairly large granules are present, lumps are formed in the felt which are apparent after the felt has been saturated with the waterproofing compound.

What I claim is 1. As a new article of manufacture a porous flexible felt sheet adapted for a foundation for prepared roofing, consisting of a thorough and intimate admixture of rag fiber, and a composition of matter comprising essentially finely shredded leather fiber and a fine spacing material.

2. As a new article of manufacture, a porous flexible felt sheet adapted for a foundation for prepared roofing, consisting of a thorough and intimate admixture of rag fiber, and a composition of matter comprising a mixture of finely shredded leather fiber and fine sawdust or its equivalent in a state of admixture.

3. As a new article of manufacture, a po rous flexible felt sheet adapted for a foundation for prepared roofing, consisting of a thorough and intimate admixture of rag fiber, and a composition of matter comprising finely shredded leather fibers, finely ground charcoal and fine sawdust.

4. A support or foundation for waterproof weatherproof prepared roofings, comprising, in thorough admixture, rag fiber and a composition of matter comprising as its essential component finely shredded leather fiber and finely divided spacing material of the nature of peat, charcoal or sawdust.

5. The herein described method of producand the said spacing material, finally beating ing felt for use in the manufacture of prethe whole mass until it is of the desired conpared roofin-gs, comprising finely shredding sistency, and then forming it in sheets. 10 leather fiber, finely dividing a spacing ma- In testimony whereof I have aflixed my 5 terial of the nature of peat, charcoal or saW- signature.

dust, beating rag stock in a heater and then mixing therewith the shredded leather fiber ALBERT L. CLAPP. 

